PPL PPL Weight and Balance 2 — Questions and Answers
Question 1: How is center of gravity (CG) location calculated?
- Total weight divided by the number of occupants
- Total moment divided by total weight (Correct answer)
- Total weight multiplied by the arm
- Total arm divided by the number of loading stations
Correct answer: Total moment divided by total weight
CG location = Total Moment ÷ Total Weight; this gives the distance of the CG from the datum in inches.
Question 2: What is the standard weight of engine oil per US gallon for weight and balance purposes?
- 6.0 pounds
- 6.7 pounds
- 7.5 pounds (Correct answer)
- 8.33 pounds
Correct answer: 7.5 pounds
Engine oil weighs 7.5 pounds per gallon, which is heavier than avgas (6.0 lbs/gal) but lighter than water (8.33 lbs/gal).
Question 3: If an aircraft is loaded beyond its maximum certificated gross weight, what is a primary safety concern?
- The aircraft will consume more fuel per hour
- Structural limits may be exceeded and performance will be significantly degraded (Correct answer)
- The aircraft will be harder to start
- Navigation communication equipment may malfunction
Correct answer: Structural limits may be exceeded and performance will be significantly degraded
Exceeding maximum gross weight can overstress the airframe (especially in turbulence or maneuvers), increase stall speed, reduce climb rate, and extend takeoff and landing distances.
Question 4: What does the CG envelope on a loading graph represent?
- The maximum amount of fuel that can be loaded for a given flight distance
- The approved combinations of aircraft weight and CG location for safe flight (Correct answer)
- The range of airspeeds at which the aircraft can safely maneuver
- The minimum and maximum altitude limits for the aircraft
Correct answer: The approved combinations of aircraft weight and CG location for safe flight
The CG envelope defines all allowable combinations of total weight and CG location; operating outside this envelope is outside the aircraft's certification and is unsafe.
Question 5: An aircraft loaded with a forward CG typically requires the pilot to do what during cruise flight?
- Apply forward pressure or trim to maintain level flight
- Apply back pressure or nose-up trim to maintain level flight (Correct answer)
- Use more aileron input to maintain wings-level flight
- Reduce power to prevent the aircraft from accelerating
Correct answer: Apply back pressure or nose-up trim to maintain level flight
A forward CG creates a nose-heavy condition requiring constant back pressure or up-elevator trim to maintain level flight, which also increases drag.
Question 6: 'Basic empty weight' of an aircraft typically includes which items?
- Airframe, engines, fixed equipment, unusable fuel, and full operating fluids (oil, hydraulic fluid) (Correct answer)
- Only the airframe weight and engine weight without any fluids
- All items aboard the aircraft including full usable fuel and maximum payload
- The aircraft with all optional and removable equipment removed
Correct answer: Airframe, engines, fixed equipment, unusable fuel, and full operating fluids (oil, hydraulic fluid)
Basic empty weight includes the airframe, engines, fixed equipment, unusable fuel, and all operating fluids (full oil, hydraulic fluid, etc.) but excludes usable fuel and payload.
Question 7: Where is the datum commonly located on many single-engine light aircraft?
- At the leading edge of the main wing spar
- At the firewall or the nose of the aircraft (Correct answer)
- At the trailing edge of the horizontal stabilizer
- At the main landing gear attachment point
Correct answer: At the firewall or the nose of the aircraft
Many light aircraft manufacturers place the datum at the firewall or at the nose/propeller flange, but the exact location varies by manufacturer and is specified in the POH.
PPL PPL Weight and Balance 2
How is center of gravity (CG) location calculated?